A new study of thousands of Medicare claims reveals that Mexican Americans aged 65 and older in four states — Texas, New Mexico, Arizona and Illinois — seek hip-replacement surgery at less than a third of the rate of non-Hispanic whites. The lead author, Agustin Escalante, M.D., associate professor of medicine at The University of Texas Health Science Center at San Antonio, says the discrepancy may lie in the fact that Hispanics facing the need for such a procedure likely do not know anyone else who has had the surgery.

Hip replacement, or arthroplasty, is a surgery in which the diseased parts of the hip joint are removed and replaced with artificial parts. These are called the prosthesis. The goals are to improve mobility by relieving pain and improve function of the hip joint. Source: National Institute of Arthritis and Musculoskeletal and Skin Diseases.

"Previous studies showed Hispanics under-use these procedures, and lack of insurance was thought to be a causative factor," Dr. Escalante said. "In this study we focused on beneficiaries of Medicare, which is something people from all ethnic groups receive upon reaching 65. It pays for total hip replacement. We eliminated the insurance variable and still came up with a disparity that is not explained by cost of procedure or insurance.

"The most likely factor is a difference in preference. Hispanics may not know someone in their neighborhood or in the bridge game at the senior center who has had a hip replacement, and that might be the difference."

The researchers, sponsored by the U.S. Agency for Healthcare Research and Quality (AHRQ), the U.S. Center for Medicare and Medicaid Services (formerly the Health Care Financing Administration), the National Institute of Arthritis and Musculoskeletal and Skin Diseases, and the Arthritis Foundation, studied Medicare claims data on 6,437 people who underwent a hip replacement between 1995 and 1996 and data on 12,874 people who did not have the surgery. "We selected Texas, New Mexico, Arizona and Illinois because they have high Hispanic populations that are primarily Mexican American," Dr. Escalante said. "We avoided states with significant Hispanic populations that are not of Mexican-American origin, such as Florida, New Jersey and New York."

He said the researchers did not rule out the possibility that arthritis, which causes degeneration in the hip and other joints, may occur less frequently in Mexican Americans than in non-Hispanic whites.

The results are published in the June issue of Medical Care, the official journal of the Medical Care Section of the American Public Health Association. Co-investigators from the Health Science Center included Inmaculada del Rincon, M.D., assistant professor of medicine, and John E. Cornell, M.D., associate professor of medicine. Jeffrey Katz, M.D., M.S., and Charlotte Phillips, R.N., M.P.H., both of Harvard Brigham and Women's Hospital, and Jane Barrett, M.S., of Dartmouth, also collaborated.

More than 160,000 total hip replacements are performed for arthritis in the United States annually. The majority of people undergoing the surgery are 65 or older. "The procedure costs about $30,000," Dr. Escalante said, "but in the long run it ends up saving money. When we can do a hip replacement, we may keep an elder out of long-term nursing care, for example."